Automatic pilot



April?,y 1940. G, CRLSQN i 2,195,406

AUTOMATIC PILOT Fd Feb. .7, l1939 i a l .as a;

lat'entedxApr. 2, 1940 UNITED STATES 2,195,406 AUTOMATIC PILOT Bert G.Carlson; Freeport, N. Y., assigner to Sperry Gyroscope Company, Inc.,Brooklyn,

N. Y., a. corporation of New rYork Application February 7, 1939, SerialNo. 255,022

3Claims.

This invention relates to automatic pilots espev cially adapted foraircraft, although the same may also be used forship's. As a base linefor steering aircraft, it isf usual to employ a directional gyroscopewhich maintains its position in space and it has also been proposed -tocombine with the same a gyroscope responsive to rate of turn, so as togive both a displacement and a rate signal to control the rudderservomotor.

While in my invention I also propose to use both a fixed base line and arate gyroscope, I prefer to employ the latter in a different man nerthan heretofore proposed. According to my l invention, I employ the rate`gyroscope merely as tion between the rudder and the displacementgyroscope. In this manner I render such follow-back unnecessary and alsosimplify the construction by bringing both signals on the same pick-offdevice at the directional gyroscope instead of combining two separatesignals at a relay or at the servomotor.

To illustrate my invention, I have shown only the azimuth control unitof an automatic pilot, butv it will be understood that my invention maybe applied to any one or all three ofthe axes of control of an aircraft.My invention is also shown as applied to the form of differential airiiow pick-olf device disclosed in the' prior patent of M. F. Bates, B.G. Carlson and Elmer A. Sperry, Jr., No. 1,992,970,dated March 5, 1935,although obviously my invention may be applied to other types ofautomatic control..

Referring to the drawing, showing one form my invention may assume.

Fig. 1 is a vertical section through the control unit box, showing boththe directional gyroscope and rate gyroscope mounted therein.

Fig. 2 is a plan view of the same with the top removed.

Fig. 3 is a detailed end elevation showing the connection between therate gyro and the followup mechanism.

Fig. 4 is a sectional detail of a limit device used '45 tor limit theadjustment of the centralizing spring on the rate gyroscope.

Both the directional gyroscope I, or other posi-l tion maintainingmeans,and the rate of turn gyroscope 2 are shown as enclosed within a commonbox 3 from which air is continuously exhausted through pipe 4 for thepurpose of spinning the gyroscopes and actuating the differential air,pick-olfy control. Said control is shown as oi the usual form, in whichthe vertical ring l5 of the directional gyroscope has thereon a asubstitute for the usual follow-back connec semlcircular cut-off plate 6positioned closely adjacent ports 1 and 8 in the rotatable follow- ,upmember 9, rotatably mounted above the plate 6. Each port is connectedthrough separate concentric channels Ill and Il with pipes- I2 and I3leading to a relay valve (not shown) for controlling the rudderservomotor. It will be evident, therefore, that upon relativedisplacement of the stabilized plate 6 and the ports 'l and 8, thedifferential air iiow through pipes I2 and I3 will be disturbed toactuate the relay.

In the usual construction, the follow-up member 9 is turned byfollow-back cables leading to the rudder. I prefer, however, to entirelyeliminate this follow-back connection and to turn the plate 9 fromtherate of turn gyroscope 2. Said gyroscope is shown as mounted forprecession about fore and aft axis I 4-I5 and is-normally centralized bya spring I 6. Preferably the tensionA of said spring is adjustable. theupper end being shown as secured to a bell crank lever Ilpivoted at I8,andthe upper end l1 of which is forked and is pivotally secured to acollar I9 swiveledon shaft 20, threaded in bracket,2l. It will readilybe apparent that by rotating the knob 22 on shaft 20, the bell cranklever Will be adjusted to vary the tension of the spring. The purpose ofthe adjustment of spring I6 is to vary the effect of the rate gyroscopeso to vary the rate of turn of the craft, the rate gyroscope acting as aspeed limiting device as well as a follow-up element. To limit theadjustment of the spring in both directions, I have shown a series ofstop pins 40 on collars 4I loosely mounted on shaft 20, the outermostpin engaging a fixed pin 42 in its limiting position. The last collar143is fixed to shaft 20, thus permitting the shaft to be rotated severaltimes in either direction, but preventing more than a predeterminednumber of revolutions thereof.

The rotor bearing'frame 24 of the turn gyroscope is `connected to shaft25, as by means of the metal strap 26 which is pinned to a pulley 2l onthe rotor bearing frame and also pinned to a pulley 28 on the shaft 25.When the gyroscope precesses in either direction, therefore, the shaft25 will be turned, which rotates the worm gear 29 on shaft 29 throughthe worm 30. Shaft 29 turns one arm of a differential gear train 45, thethird arm of said train turning a large gear 3| meshing with a similargear 32 secured to the rotatable ported member- 9, so as to turn thesame. Hence the member' 9 will be rotated, whenever the rate gyroprecesses, an amount delpendent on the rate of turn of the craft andlinf trolled from a remotely located course change valve (not shown).

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingshall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim land desire to secure byLetters Patent is:

1. In a control unit for automatic pilots for 'dirigible craft, aposition maintaining device, a

rate of turn gyroscope, a two part controller at the said device, onepart of which is stabilized irom said device, and means 'connecting saidgyroscope and the other part of said controller to cause said other partto follow the first part as the craft turns in response to a signal fromsaid controller.

2. In a control unit for automatic pilots as claimed in claim 1 in whichsaid rate gyroscope is provided with a centralizing spring and means foradjusting the tension of said spring to vary to resultant rate of turnof the craft.

3. In a control unit for automatic pilotsjfor dirig'lble craft, adirectional gyroscope, a rate of turn gyroscope adjacent thereto, adifferential air-ilow two-part pick-off device at said directionalgyroscope, one part of which is stabilized therefrom, and a mechanicalconnectionl from said rate gyroscope to the other part of said pick-oil'device causing turning of saidv other part responsive to turn of thecraft.

BERT G. CARLSON.

